Everything You Need To Know About B12 Deficiency + How To Get Enough

Vitamin B12 deficiency is often described as “sneaky” since it can be so difficult to pinpoint and diagnose. While clinical deficiencies are considered rare, subclinical deficiencies—meaning they’re not captured on traditional lab tests—can affect up to 26% of the population—an even sneakier problem. Because an untreated vitamin B12 deficiency can result in lasting effects, it’s important to recognize the signs and the risk factors as early as possible.

B12 is also essential for keeping your brain and nerves healthy and for making new DNA. The vitamin also helps lower levels of homocysteine1, an amino acid that’s been linked to heart disease, stroke, dementia and osteoporosis. 

Because the signs of B12 deficiency are so widespread, it’s often difficult to recognize. You may have a handful of mild symptoms, or a more extensive list of severe symptoms. Some of the most common signs of B12 deficiency are:

And researchers from a study that was published in Applied Physiology, Nutrition, and Metabolism noted that If vitamin B12 deficiency isn’t corrected, it can lead to long-term complications, like:

There have even been some reports that severe vitamin B12 deficiencies can present as drug-resistant schizophrenia and/or psychosis.

Even if you’re consuming adequate amounts of B12, you can develop a B12 deficiency as a result of:

Pernicious anemia is a condition in which the body doesn’t make adequate amounts of a protein called intrinsic factor. Intrinsic factor attaches to B12 and carries it to the intestines, where it’s absorbed into your blood. If you don’t make enough intrinsic factor, your body can’t absorb adequate amounts of vitamin B12, no matter how much you eat.

Digestive conditions that interfere with the way your body absorbs nutrients, like Crohn’s disease and Celiac disease, increase your risk of developing a B12 deficiency.

As you get older, your stomach gradually produces less stomach acid3, which is vital for the proper digestion and absorption of vitamin B12. If you don’t have enough stomach acid, your body can’t access what it needs.

Heartburn medications and proton pump inhibitors (PPIs) reduce the amount of stomach acid your body makes. And since you need adequate amounts of stomach acid to properly absorb vitamin B12, regularly taking this class of medications can increase your risk of a deficiency4.

The common diabetes medication, Metformin, can also increase your risk of developing vitamin B12 deficiency, although it’s not entirely clear how many people this affects. According to a report that was published in BMJ, the reported prevalence of B12 deficiency connected to Metformin ranges from around 6% to 52%—a huge range.

Heather Moday, M.D., a functional medicine immunologist and allergist, adds that B12 deficiency often comes down to—you guessed it—your gut. "B vitamin deficiencies tend to go hand in hand with gut problems," she previously told mbg.

For example, if you take folic acid supplements or get a lot of folic acid through fortified foods, it can mask a B12 deficiency. Intrinsic factor antibodies can also produce false results, making it seem like you have enough B12 in your blood when you don’t.

Our bodies don’t make vitamin B12. And since it’s a water-soluble vitamin, your body doesn’t store any extra either. It uses what it needs and then expels the rest when you pee. That means you have to make sure you’re consuming enough vitamin B12 every day to meet your needs—around 2.4 micrograms per day (unless you’re pregnant or breastfeeding, then that number jumps to 2.6 and 2.8 micrograms, respectively). If your diet falls short, or you have a condition that prevents the proper absorption of vitamin B12, you may need some help getting what you need.

As with any nutrient, it’s important to get what you can from foods. The richest food sources7 of vitamin B12 are:

And while there aren’t many natural vegan and vegetarian sources of B12, there are some foods, like nutritional yeast and breakfast cereals that are fortified with the vitamin.

If you have gut issues, Myers recommends a sublingual—or liquid—B12 supplement. If you have pernicious anemia or a severe deficiency, you’ll need regular B12 injections. Head’s up: These can only be administered by your doctor or a licensed healthcare provider, so if you fall into this camp, make sure you’re working closely with someone who knows your medical history and can help you navigate the proper treatment.

Your body relies on vitamin B12 for healthy blood cells and a properly functioning nervous system, but even if you’re eating plenty of B12-rich foods, you still may not be absorbing the vitamin properly. If you suspect a deficiency, work with your doctor to get the proper tests so you can start on a natural treatment plan that gets your levels corrected in a way that works for you.